Toy building block



FIG. 1 is a front perspective view of a toy building block showing my new design;

FIG. 2 is a perspective view of the side opposite that shown in FIG. 1;

FIG. 3 is a front perspective view of a modified embodiment of the design shown in FIGS. 1 and 2; and,

FIG. 4 is a perspective view of the side opposite that shown in FIG. 3. 

The ornamental design for a toy building block, as shown and described. 